Delustered regenerated cellulose sausage casings

ABSTRACT

Tubular sausage casings of regenerated cellulose which are soft and flexible and delustered in appearance have droplets of colloidal size, e.g. less than about 0.06 mm., dispersed throughout the film in a concentration of 0.1 - 12% wt. based on the cellulose, said droplets being a mixture of different delusterant materials.

United States Patent 1191 [111 7 3,833,021 Rose eta1. *Sept. 3, 1974DELUSTERED REGENERATED CELLULOSE SAUSAGE CASINGS [56] References Cited[75] Inventors: Henry J. Rose; Albin F. Turbak, UNITED STATES PATENTSboth of Danville, 111. 1,956,034 4/1934 Kline 106/166 2,060,016 11/1936Barthelemy.... 106/166 [73] Asslgnee: Inc, Chlcago, 2,081,847 5/1937Byron et a1. 106/166 =1: 1 Notice: The portion of the term of this2,275,199 3/1942 Printon .1 106/166 patent Subsequent to Sept 21,3,607,328 9/1971 Kose et a1. 106/166 1988 has been dlsclalmed PrimaryExaminerMorris O. Wolk [22] F1led: Apr. '10, 1972 AssistantExaminer'Sidney Marantz [211 p NO 242 755 Attorney, Agent, or Firm-NealJ. Mosely; Russell L.

' Brewer Related US. Application Data [63] Continuation of Ser. No.102,958, Dec. 30, 1970, [57] I ABSTRACT aNbandoned Much is acommuation'in'pan of Tubular sausage casings of regenerated cellulose j'gj h fg i 3 which are soft and flexible and delustered in appeare a anone ance have droplets of colloidal size, -e.g. less than about 0.06mm., dispersed throughout the film in a [52] Cl 138/118'l fconcentration of 0.1 12% wt. based on the cellulose, [51] Int Cl i 13/00said droplets being a mixture of different delusterant 58 Field ofSearch 99/176; 106/166, 168; matenals 138/1 18.1 8 Claims, No DrawingsDELUSTERED REGENERATED CELLULOSE SAUSAGE CASINGS CROSS-REFERENCE TORELATED APPLICATIONS This application is a continuation of applicationhaving Ser. No. 102,958, filed Dec. 30, 1970, and now abandoned whichwas a continuation in part of application Ser. No. 763,942, Sept. 30,1968, now US. Pat. No. 3,607,328 and of application Ser. No. 431,181,filed Feb. 8, 1965 now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to the production of delustered cellulosic sausage casings.Cellulosic sausage casings are ordinarily produced bythe viscose processand are optically clear. For certain applications, there is a demand fora cellulosic casing which is delustered to produce a milky opalescentappearance.

2. Description of the Prior Art In the art of rayon manufacture and tosome extent in the cellophane art, there has been considerable work donein the preparation of delustered regenerated cellulose products. KochUS. Pat. No. 1,951,094 discloses the use of metal soaps and emulsions indelustering rayon fibers. Nonamaker US. Pat. No. 1,822,416 discloses theuse of ground cellulose particles in delustering rayon fibers.Chavassieu US. Pat. No. 2,034,771 discloses the preparation ofdelustered rayon resembling natural wool in appearance by incorporationof sulfur particles therein. Kline US. Pat. No. 2,077,700 discloses theuse of chlorinated organic materials in delustering rayon. LilienfeldUS. Pat. No. 2,021,863 discloses the use of various thiocarbonic estersas delustering agents in rayon. Gloor US. Pat. No. 2,227,495 disclosesthe use of terpenes and terpene ethers as delustering agents for rayon.Hegan and Taylor US. Pat. No. 1,922,952 discloses the incorporation ofmineral oil and sulfonated oils into viscose for the preparation ofdelustered filaments, threads, and bands. Stockly and Witte US. Pat. No.1,902,529 discloses the use of waxes in viscose for preparation ofdelustered rayon. Borzykowski US. Pat. No. 2,057,323 teaches the use ofproteins in viscose as delustering agents. Dreyfus U.S. Pat. No.3,042,702 discloses the use of silicate esters in the preparation ofdelustered filaments. Smith US. Pat. No. 2,334,358 discloses thedelustering of rayon filaments with titanium oxide pigments.Hirschberger 1,819,241 discloses the treatment of rayon fibers withsolutions of wax in oil. Byron et al. 2,081,847 discloses theapplication of delustering agents in solution in a volatile organicsolvent. Karplus 2,166,741 discloses the introduction of delusteringagents in certain volatile organic solvents.

The various types of delusterants described in the rayon art have notproved entirely satisfactory in the preparation of cellulose films or inapplication to other types of transparent or translucent extrudedproducts.

SUMMARY OF THE INVENTION This invention is based upon our discovery of anovel process for preparing delustered cellulosic sausage casingsutilizing the viscose process. We have found that delustered cellulosiccasings may be prepared having a substantial delustering effect andlittle loss of tensile strength by incorporating into viscose a solutionof at least two different delustering agents in a cosolvent which issoluble in viscose. The delustering agents used are substantiallyimmiscible with each other and with viscose or with regeneratedcellulose and are added in solution in a cosolvent which is soluble inviscose. The delustering agents have a refractive index which issubstantially different from each other and from the regeneratedcellulose.

When the solution of two different delustering agents in a cosolvent isdispersed into viscose, it forms a fine dispersion or fog throughout theviscose and the cosolvent dissolves in the viscose to leave behind mixeddelusterant particles of substantially smaller size and substantiallygreater delustering effect than is possible by utilization ofdelustering agents either singly or applied in combination byotherprocedures.

DESCRIPTION OF THE PREFERRED EMBODIMENTS This invention comprises newand improved delustered cellulosic sausage casings. In making thesecasings, two or more delustering materials, which may be solid, liquidor gelatinous in form, having an index of refraction substantiallydifferent from each other and from regenerated cellulose, are added toviscose in solution in a cosolvent. Typical delusterants which may beused include but are not limited to fatty or waxy materials, such asfats, fatty oils such as castor oil, lard oil, corn oil, soya oil,safflower oil, tung oil, etc., vegetable waxes, animal waxes, mineralwaxes, or fatty or waxy derivatives thereof, polyethylene waxes, mineraloils, fatty monoglycerides, and partially or fully acetylated fattymonoglycerides.

The delusterants are added in solution in co-solvents which are selectedfor chemical inertness, easy removal, and utility as solvents for thedelusterants. Suitable co-solvents include dioxane, tetrahydrofuran,dimethylformamide, carbon disulfide, dimethyl sulfoxide, and othersolvents which are soluble in viscose.

When two or more different delustering agents are dissolved in theco-solvent and dispersed into viscose as an emulsion or dispersion offine droplets, the cosolvent is rapidly dissolved into the viscose withthe result that the mixture of. delustering materials forms even smallerdroplets of mixed character which produce'a high degree of delusteringwithout substantial loss of tensile strength of the regeneratedcellulose product. The viscose, with the delusterant dispersed therein,is extruded through a conventional annular die into coagulating andregenerating baths, in accordance with well known procedures for thepreparation of regenerated cellulose casings. After washing and drying,the casing produced has a semi-opaque or translucent appearancecharacteristic of a highly delustered film.

In carrying out this invention it is absolutely essential that thedelustering materials be dissolved and added together in a co-solvent tothe viscose prior to extrusion. In extensive experimental work, it wasfound that the addition of single delustering materials did not producecomparable delustered casings regardless of the degree of dispersion orthe loading of the delusterant in the film. It was also found that theaddition of delustering materials separately in the preparation of thefilm, as distinguished from addition of delusterants in a co-solvent,resulted in the production of film having a substantially poorerdelusterant effect.

The following non-limiting examples are illustrative both of certainunsuccessful attempts to prepare delustered casings by other proceduresand are illustrative of several satisfactory procedures for preparingdelustered casings demonstrating the scope of this invention.

EXAMPLE 1 A commercial viscose was prepared having a 7.7% cellulosecontent and used to cast a number of films for evaluating theeffectiveness of certain delustering materials. A small portion of theviscose was used to hand cast a 22 mil film on a glass plate using adrawbar. The film was coagulated and regenerated using conventionalcoagulation and regeneration baths. The film produced in this manner hada wet thickness of 3.6 mil and a dry thickness of 1.8 2.0 mi]. The filmwas rewet and tested on an lnston tester for tensile strength. The rewetclear regenerated cellulose film was found to have a tensile strength of3194 p.s.i.

EXAMPLE 2 A commercial viscose was prepared having a 7.7% cellulosecontent, as in Example 1. To this viscose, there was added a solutionconsisting of 1 part mineral oil admixed with 1 part tetrahydrofuran inan amount sufficient to produce an oil concentration in the viscose of4% by weight calculated on the weight of cellulose present. The mineraloil in solution in tetrahydrofuran was mixed thoroughly into the viscoseto produce a milky dispersion of the mineral oil.

The mixture of oil and viscose was then'used to cast a 22 mil film on aglass plate using a drawbar, as in Example l. The film was coagulatedand regenerated using conventional coagulation and regeneration baths.The film thus produced had a wet thickness of 3.7 mil and a drythickness of 2.4 mil. The film was rewet and tested in an lnston tester,as in Example 1, and found to have a tensile strength of 2265 p.s.i.

The oil modified regenerated cellulose film thus produced was observedfor delustering effect and found to have a rather poor delustering. Thefilm was observed under a microscope and found to have oil particlesranging from 0.02 to 0.12 mm. in diameter, with the larger dropletspredominating. The droplets appear to be transparent under magnificationbut give a relatively opaque appearance to the film with a rather poordelustering effect.

EXAMPLE 3 In this example, a commercial viscose, 7.7% cellulose contentwas mixed with a vegetable oil, castor oil, to determine its delusteringeffect. A solution was prepared consisting of 1 part of castor oil and 1part of tetrahydrofuran. A sufficient quantity of the solution was addedto the viscose and thoroughly mixed therein to 'produce a dispersion ofcastor oil in a concentration of on an lnstron tester. The caster oilmodified film had a rewet strength of 2621 p.s.i.

The castor oil modified film was evaluated both by macroscopic andmicroscopic visual examination. On the macroscopic level, the film wasobserved to have a weak luster but a lowered light transmission (loss ofbrightness) the delustering effect was rather poor. On the microscopiclevel, the castor oil dispersion in the regenerated cellulose film wasobserved to consist of oil droplets ranging from 0.01 0.02 mm. indiameter. These droplets are relatively clear optically on a microscopiclevel but tend to opacify the film slightly.

EXAMPLE 4 In this example, a study was made of the delustering effect oftwo different oils added separately to viscose. A commercial viscose,7.7% cellulose content, was used in the previous examples and dividedinto two separate parts. Two separate solutions were prepared consistingof 1 part of mineral oil in 1 part tetrahydrofuran and 1 part castor oilin 1 part tetrahydrofuran. The mineral oil solution was added andthoroughly mixed in one of the viscose aliquots. The castor oil solutionwas added and thoroughly mixed in the other aliquot and the resultingviscose-oil solutions were then mixed together. The mineral oil andcastor oil were each added in an amount equal to 2% of each based on theweight of cellulose in the total solution.

The mixture of oils and viscose was cast on a glass plate with a drawbarproducing a 22 mil wet film. After coagulation and regeneration with aconventional ammonium sulfate and sulfuric acid treatment, there wasobtained a regenerated cellulose film having a wet thickness of 3.6 miland a dry thickness of 2.0 mil. This film was rewet and tested fortensile strength on the Instron tester. The film had an average tensilestrength of 2700 p.s.i.

The regenerated cellulose film containing mixed droplets of mineral oiland castor oil was evaluated both on a microscopic and macroscopic levelfor delustering. The luster of the film was quite weak when observed ona macroscopic level. When the film was observed in the microscope, itwas found to have a plurality of separate mineral oil and castor oildroplets ranging in size from 0.02 to 0.06 mm. The individual oildroplets were relatively clear optically. This film was observed to havea moderately good delustering but was too transparent to be satisfactoryfor commercial use.

EXAMPLE 5 In this example, a mixture of two different oils is applied toa viscose in accordance with this invention to produce a highlydelustered film. A commercial viscose is prepared, as in the previousexamples having a 7.7% cellulose content. To this viscose, there wasadded a solution consisting of 1 part mineral oil and 1 part castor oilin 2 parts tetrahydrofuran. The solution of mineral oil and castor oilin tetrahydrofuran was added in an amount sufficient to produce aconcentration of 2% of each of the oils based on the weight of cellulosepresent. The solution was admixed thoroughly with the viscose and a fogof fine droplets of oil produced throughout the viscose.

The mixture of oils and viscose was cast on a glass plate with a drawbarto produce a 22 mil film. The film was coagulated and regenerated usinga conventional coagulation and regeneration treatment as in the otherexamples. The regenerated cellulose film thus produced had a wetthickness of 3.5 mil and a dry thickness of 1.8 2.0 mi]. The film wasrewet and measured on the lnstron tester for tensile strength. This filmhad a tensile strength of 3142 p.s.i., which is essentially the same asthe control. In fact, the change in tensile strength of this sample inrelation to control is within experimental error for the test equipmentand the method of testing used.

The regenerated cellulose film containing the mixed oils added intetrahydrofuran solution was evaluated both macroscopically andmicroscopically for delusterant effect. On the macroscopic level, thefilm was observed to have a satisfactory luster and appeared to have asoft translucent opalescent sheen. The film had physical properties,both tensile strength elongation at break, corresponding substantiallyto that of the control sample. When the delustered film was observedunder the microscope, it was found to contain a large number of smalloil droplets ranging in size from 0.01 to 0.04 mm. The droplets wereeach opalescent or translucent due to the colloidal dispersion of theindividual oils each in the other within the individual dorplets. Itshould be noted that the individual droplets produced in the film inthis example are droplets wherein the oils are present in two phases,i.e., each oil is dispersed within the other and does not separate inthe formation of the-oil dispersion in the viscose. This mixture of oilswithin the individual droplets results in the droplets themselves beingopalescent and contributing a greater delustering effect than ispossible using separate oil droplets as in the other examples.

In carrying out the preparation of a delustered film in accordance withthis example, any mixture of two different oils or similar materialshaving different refractive indexes may be used provided that the twoseparate delustering materials are dissolved in a cosolvent, such astetrahydrofuran or the like, which is soluble in viscose. It isnecessary that the co-solvent be soluble in viscose so that when the oilsolution is dispersed in the viscose, the solvent will dissolve rapidlyaway from the oils and leave the oils in a mixed form producing thetwo-phase opalescent droplets observed in the microscopic examination ofthe film.

EXAMPLE 6 A commercial viscose was prepared having a 7.7% cellulosecontent. To this viscose, there was added a solution consisting of 3parts mineral oil and 3 parts castor oil in 8 parts of 1,4-dioxane. Thesolution was finely dispersed in the viscose in an amountsufficient toproduce a mixed oil content of 3% inthe regenerated cellulose product. i

The mixture of oils and viscose was extruded through an annular die toproduce a tubular casing in accordance with well known procedures forthe preparation of regenerated cellulose casing. The viscose-oil mixturewas extruded through a die into a conventional coagulating andregenerating bath and subsequently washed and dried.

The washing and drying of the regenerated cellulose casing was effectiveto remove all of the dioxane from the product and leave a highlydelustered cellulose casing. When the solvent is washed and/orevaporated from the regenerated cellulose casing, there are formed alarge quantity of opalescent particles or droplets dispersed throughoutthe wall of the casing. The droplets EXAMPLE 7 A commercial viscose wasprepared having a 7.7% cellulose content, To this viscose, there wasadded a solution consisting of 3 parts mineral oil and 3 parts castoroil in 6 parts of tetrahydrofuran. The solution was finely dispersed inthe viscose in an amount sufficient to produce a mixed oil content of 4%in the regenerated cellulose product.

The mixture of oils and viscose was extruded through an annular die toproduce a tubular casing in accordance with well known procedures forthe preparation of regenerated cellulose casing. The viscose-oil mixturewas extruded through a die into a conventional coagulating andregenerating bath and subsequently washed and dried.

The washing and drying of the regenerated cellulose casing was effectiveto remove all of the tetrahydrofuran from the product and leave a highlydelustered cellulose casing. When the solvent is washed and/orevaporated from the regenerated cellulose casing, there are formed alarge quantity of opalescent particles or droplets dispersed throughoutthe wall of the casing. The droplets are opalescent as a result of thedispersion of one of the oils into the other upon precipitation from thetetrahydrofuran co-solvent. The removal of the solvent effects theproduction of extremely fine opalescent particles or droplets dispersedto yield a more highly delustered casing film.

The delustering materials may vary from 0.1 to 12% weight of theregenerated cellulose casing without substantial loss in casing strengthand produce a delustered product at all concentrations within thisrange. The delusterant materials are present in the casing in the formof droplets of a size less than 0.6 mm. which comprise a mixture ofdelusterants.

The delustered products which are produced in accordance with thisinvention are satisfactory as casings for food packaging or forprocessing of sausage meats. The delusterant materials used arenon-toxic, The process used in preparing this delustered product iseffective for producing an ultrafine colloidal dispersion of twodifferent delustering materials within the film product. The use of twodifferent delustering materials dissolved in a co-solvent which issoluble in viscose is effective for producing a finer dispersion ofdelusterant droplets or particles and thus produces a superiordelustering effect. The delustering effect which is obtained utilizesnot only the individual fine opalescent droplets of delusteringmaterials but also the formation of ultra-fine droplets or particles ofone delustering material within droplets of the other delusteringmaterial. The process is simple and inexpensive to carry out andproduces novel products with a higher delustering effect than has beenproduced by prior art techniques.

We claim:

l. A tubular sausage casing of regenerated cellulose which is soft anddelustered in appearance having droplets dispersed therein of a sizeless than 0.06 mm., in a concentration of 0.1 12% wt. based on thecellulose, said droplets being a mixture of different delusterantmaterials having a refractive index substantially different from eachother and from the regenerated cellulose.

2. A casing in accordance with claim 1 in which said droplets eachcomprise a colloidal dispersion of one delusterant material in anotherdelusterant material and are opalescent in appearance.

3. A casing in accordance with claim 1 in which the delusterantmaterials are fats, oils, or waxes, or fatty or delusterant materialsare castor oil and mineral oil.

2. A casing in accordance with claim 1 in which said droplets eachcomprise a colloidal dispersion of one delusterant material in anotherdelusterant material and are opalescent in appearance.
 3. A casing inaccordance with claim 1 in which the delusterant materials are fats,oils, or waxes, or fatty or waxy derivatives thereof.
 4. A casing inaccordance with claim 1 in which the delusterant materials are avegetable or animal fatty oil and a mineral oil.
 5. A casing inaccordance with claim 1 in which the delusterant materials are castoroil and mineral oil.
 6. A casing in accordance with claim 2 in which thedelusterant materials are fats, oils, or waxes.
 7. A casing inaccordance with claim 2 in which the delusterant materials are avegetable or animal fatty oil and a mineral oil.
 8. A casing inaccordance with claim 2 in which the delusterant materials are castoroil and mineral oil.